The Jerusalem Post has a preliminary report. It appears to have been posted minutes ago.
Injured count up to 20 now.
According to the Jerusalem Post:
The head of police in Jerusalem announced on Monday evening that the bus explosion in the capital earlier in the day was caused by a bomb. He said there was no doubt that the incident was a terrorist attack.
At least 20 people were injured by an explosion on a bus in Jerusalem, police said Monday. It was not immediately clear if the explosion was terror related.
It was earlier reported that Police were investigating whether one of the critically injured in the explosion was carrying a small explosive device.